An internal combustion engine system ordinarily involves the engine, an exhaust muffler which, through an exhaust pipe, receives the engine's exhaust and discharges it to the atmosphere, and means for supplying the engine with a suitable fuel mixed with adequate air to support combustion in the engine.
Such a system is commonly used to power automobiles, trucks and automotive vehicles in general. The fuel normally used today is gasoline containing lead and/or aromatic hydrocarbons to provide an octane number high enough to prevent pre-ignition in the engine. The resulting engine exhaust is blamed for the current atmosphere pollution problem.
Miniaturized apparatus has been developed which produces an engine fuel in the form of gas containing carbon monoxide, methane and/or hydrogen and having a more than adequate high octane number, when the reformer is supplied with low octane fuel as exemplified by aliphatic, straight-chain hydrocarbons of short chain length, such as C.sub.7 H.sub.16, for example. Normal anti-knocking agents, such as lead and/or aromatic hydrocarbons, need not be used with their attendant harmful atmosphere polluting effects. The use of the gas effects a substantial reduction in the engine exhaust content of nitrogen/oxide compounds which are today considered particularly objectionable as atmospheric pollutants. If the liquid fuel does contain aromatic hydrocarbons, these are decomposed into harmless components by such apparatus. The use of gasolines low in atmospherically harmful substances are generally available from existing networks of gasoline filling stations.
Such a miniaturized apparatus is hereinafter called a gas reformer. Very briefly stated, it comprises one or a series of small porous catalytic carriers which are heated and fed with a mixture of liquid hydrocarbon, such as gasoline, in vaporized form and mixed with oxygen-containing gas, such as the engine's exhaust and/or air, or a mixture of both, the output of the reformer being the gas containing carbon monoxide, methane, and/or hydrogen, which, with the addition of air, is fed to the internal combustion engine. This resulting gas is hereinafter called a reformed gas.
Each catalyst carrier is in the form of a highly porous body made of sintered particles and through which is formed a multiplicity of small holes through which the vaporized liquid fuel and oxygen containing gas mixture passes, the body containing a suitable catalyst in its pores which at elevated temperatures results in changing the liquid fuel to the gas fuel. Usually a series of such carriers are used.
Such a reformer may be compactly encased with miniaturized transverse dimensions and length, even when including possible accessory equipment. The overall dimensions permit the encased reformer to be positioned beside the engine such as under the engine hood, in normal automotive applications, as an example of its miniaturized size.
However, to heat the reformer to its elevated operating temperature, it has been enclosed by a larger heat enclosure forming a space around the reformer through which the engine exhaust is passed in heat-exchanging relation to the reformer for the latter's heating. This has the disadvantage that although the reformer is miniaturized the larger surrounding enclosure increases its overall size or bulk to an undesirable degree. This is particularly true in automotive installations where there is a large amount of already existing equipment in the engine space available. Furthermore, the reformer's intake heating, heat exchange requires piping to pass the exhaust through and from this device.
Examples of the type of reformer referred to are shown by German Pat. application Nos. P 21 03 008.0 and P 21 35 650.3 (Henkel et al., U.S. Ser. No. 270,923, filed July 12, 1972).